1. Field of the Invention
The invention relates in general to an electronic apparatus, AC/DC conversion device and power factor correction (PFC) circuit thereof, and more particularly to an electronic apparatus, AC/DC conversion device and power factor correction circuit thereof, which can reduce electromagnetic interference (EMI) by using a spread spectrum signal.
2. Description of the Related Art
Referring to FIG. 1, a block diagram of a conventional projector is shown. A projector 100 includes a power factor correction circuit 110, a flyback converter 120, a lighting circuit 130 and a lamp 140. The power factor correction circuit 110 is a power supply for the projector 100. The power factor correction circuit 110 supplies a high DC voltage about 380V to the lighting circuit 130 and the flyback converter 120. The lighting circuit 130 is, for example, a ballast for lighting up the lamp 140. The flyback converter 120 supplies a DC power of 12V, 5V and 3.3V, for example.
However, there usually occurs electromagnetic interference between electronic apparatuses. Therefore, intensity of the electromagnetic waves generated by the electronic apparatuses should be suitably limited. For example, American federal communication commission (FCC) sets up a standard for limiting radiation quantity of electronic products. However, the issue that the power factor correction circuit easily causes electromagnetic interference to other electronic apparatus is still not resolved.